Epigenetic regulation of flower
development in the oil palm
Alain RIVAL, Thierry BEULE, Frédérique RICHAUD, Pascal ILBERT,
Estelle JALIGOT
CIRAD, UMR DIADE, Montpellier, France
Plant and Animal Genome XX
Palm Genomics and Genetics Workshop January 15, 2012
Why studying the oil palm at all?
• Because it is the 1st world source of
vegetable oil and consumption for food and energy can only rise with
increasing population.
• Because its mantled floral phenotype provide an original model where
agro-economical interests fuel the search for basic knowledge in a tropical perennial.
Characteristics of the mantled phenotype
• Somaclonal variation: arises from in vitro cloning
• Alteration of floral organs:
poor oil accumulation, infertility, visible in adult trees only
• Highly heterogeneous: frequency, severity, genotype effect
• Unstable: spontaneous reversion
Normal fruit
Slightly mantled fruit
Dealing with mantledness from
both ends of the cloning process
• Working on adult palms to understand the molecular
origin of the floral phenotype
• Working on in vitro cultures to test potential markers
for early detection
Somatic embryogenesis
A few things we know about mantled
• No genetic/cytologic alteration • Non-mendelian inheritance
• Hypomethylated genome
• Altered gene transcription
• Phenotype: stamen converted into carpels,
reminiscent of B-class MADS-box gene mutants
The hypothesis
• Epigenetic mechanisms regulating gene
expression are perturbated by the cloning process (hormones, re-programming)
• Most of these alterations have no detectable
impact on the phenotype and/or subside
• The pathway governing floral organ
formation remains affected in the adult stage (sensitivity shared amongst Palms?)
• In vitro material: investigating the
genomic and epigenetic stability during the tissue culture process
• Adult (inflorescence) material:
exploring the epigenetic regulation of flower development
• In vitro material: investigating the
genomic and epigenetic stability during the tissue culture process
• Adult (inflorescence) material:
exploring the epigenetic regulation of flower development
The strategy
Follow-up on the phenotypic stability
• In vitro material: investigating the
genomic and epigenetic stability during the tissue culture process
• Adult (inflorescence) material:
exploring the epigenetic regulation of flower development
The strategy
Tracing back the origin of the mantled
Investigating the stability of cell cultures
Seed-derived palm Normal regenerant Mantled regenerant Cloning 1Investigating the stability of cell cultures
Seed-derived palm Normal regenerant Mantled regenerantPropagation over 1 year, periodical samplings for DNA/RNA extractions
« Normal » cell lines « Mantled » cell lines
Cloning 1
Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Chanderbali et al., 2010 Polycomb-group genes Transcription factors T ran sp o sab le E lem en ts
RNAseq, Q-PCR
Exploring the epigenetic
regulation of flower development
Floral MADS-box genes
Chanderbali et al., 2010 Polycomb-group genes Transcription factors T ran sp o sab le E lem en ts Bisulfite, ChIP
Different epigenetic marks in
mantled flowers?
Different mRNA/sRNA levels in mantled flowers?
Thank you for your attention
« Things written in pen you can’t change. That’s DNA.
But things written in pencil you can. That’s epigenetics »
Danielle Reed, geneticist
